This invention relates generally to a control circuit for an electric program shutter in which the aperture opening gradually increases with the lapse of time and the aperture remains fully opened during the exposure time and more particularly, to a shutter control system capable of introducing exposure information, such as the object distance and the guide number which are necessary for flash photography, to the time control circuit in flash photography using a shutter having a time control circuit capable of controlling the aperture opening. This invention is also capable of providing a non-synchronousness warning by means of an indicator element prior to the shutter operation in the flash photography mode in such cases when the aperture opening calculated using informations such as the object distance and the guide number exceeds the full aperture. In the conventional shutters, the proper aperture opening determined in dependence on the object distance and the guide number is manually adjusted or determined by means of a mechanical interlocking mechanism and, therefore, the conventional shutters require complicated mechanism and parts and have a disadvantage that the non-synchronousness warning by means of an indicator element, such as easily practiced by the present invention, is difficult to achieve in conventional shutters. Accordingly, an object of the present invention is to eliminate the disadvantage of the conventional shutter system by electrically introducing the exposure information for flash photography.